JP2009176878A - Electromagnetic actuator and injector of common-rail type diesel engine including the same actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve response performance of operation in an electromagnetic actuator that is driven with an electromagnetic force of an electromagnet. <P>SOLUTION: A housing 2 of injector 1 of the common-rail type diesel engine includes a movable part 12 displaced on the basis of the electromagnetic force of the electromagnet 11 and an electromagnetic valve 10 supported with a bearing 18 to include a drive axis 13 displaced together with the movable part 12. An orifice hole 17 is opened by driving the drive axis 13 through control of power feeding of the electromagnet 11 and a fuel injection is actualized by lowering fuel pressure of a back pressure control chamber 20. Meanwhile, the orifice hole 17 is closed with a valve 14 by suspending power feeding of the electromagnet 11 and fuel injection is suspended by displacing a needle valve 23 in the direction of an injection hole 3 with the fuel pressure of the back pressure control chamber 20. These movable part 12 and drive axis 13 are formed of a ceramic material and a magnetic material to be magnetized is supported with the movable part 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic actuator and an injector of a common rail type diesel engine including the same.

  Conventionally, for example, as a fuel injection system that supplies high-pressure fuel to each cylinder of a diesel engine, a high-pressure fuel pump that pressurizes fuel supplied from a fuel tank and fuel pressurized by the high-pressure fuel pump are stored in a high-pressure state. There is known a so-called common rail fuel injection system that includes a common rail that performs fuel injection and an injector that injects fuel stored in the common rail into each cylinder.

  The injector of the common rail fuel injection system includes a needle valve that opens and closes a nozzle hole, a spring that biases the needle valve toward the nozzle hole, a back pressure control chamber that controls opening and closing of the needle valve, and back pressure control. And an electromagnetic valve that opens and closes the opening of the overflow passage connected to the chamber (see, for example, Patent Document 1 and Patent Document 2).

The electromagnetic valve includes a movable portion that is displaced based on the electromagnetic force of the electromagnet, a drive shaft that is supported by the bearing and is displaced together with the movable portion, and a valve portion that is formed on the drive shaft. It is opened and closed by displacing the movable part and the drive shaft through control. When the solenoid valve is opened, the fuel in the back pressure control chamber flows out into the overflow passage and the fuel pressure in the back pressure control chamber decreases, so the needle valve opens the nozzle hole, and fuel flows from the nozzle hole. Be injected. On the other hand, when the solenoid valve is closed, fuel is supplied from the common rail and the pressure in the back pressure control chamber is maintained at a high pressure. Therefore, the needle valve closes the injection hole by the urging force of the spring, and fuel injection is stopped.
JP 2003-328812 A JP 2005-307790 A

  By the way, in such a common rail type fuel injection system, in general, multistage injection that injects a minute amount of fuel in a short period of time such as pilot injection, post injection, or split injection is executed, and thus precise fuel injection control is required. The However, in injectors in conventional common rail fuel injection systems, including those described in Patent Document 1 and Patent Document 2, the inertia force of the movable part and the drive shaft acts when opening and closing the electromagnetic valve. The operation responsiveness of the valve is low, which is a factor that hinders the improvement in accuracy of fuel injection control.

  Such problems related to operation responsiveness are not limited to the electromagnetic valves used in the injectors of the common rail fuel injection system as described above, but are generally common to electromagnetic actuators driven by electromagnetic force of electromagnets. Yes.

  The present invention has been made in view of such circumstances, and an object thereof is to improve the operation responsiveness of an electromagnetic actuator that is driven by the electromagnetic force of an electromagnet.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is an electromagnetic actuator comprising a movable portion that is displaced based on an electromagnetic force of an electromagnet and a drive shaft that is displaced together with the movable portion, wherein the movable portion and the drive shaft are formed of a ceramic material. The gist of the invention is that the movable part carries a magnetizable magnetic material.

  According to this configuration, since the movable portion is made of a ceramic material and carries a magnetic body, it can be provided with magnetizability. Since both the movable part and the drive shaft are made of a ceramic material, the weight of the movable part and the drive shaft can be reduced, and the operation response of the electromagnetic actuator can be improved. Become.

  The gist of the invention according to claim 2 is that, in the electromagnetic actuator according to claim 1, at least one of the drive shaft and the movable portion is guided by the guide portion when displaced.

  According to this configuration, since the drive shaft and the movable portion are made of a ceramic material, it is possible to suppress the occurrence of wear and seizure of the portion guided by the guide portion as compared with the case of being formed of a metal material. .

  Further, as a specific configuration for imparting magnetizability to the movable part, as in the invention according to claim 3, the movable part is formed by sintering a ceramic powder mixed with a magnetic powder. It is possible to adopt a configuration in which a magnetic material layer made of a magnetic material is laminated on a surface of the movable portion facing the electromagnet as in the invention described in claim 4.

  A fifth aspect of the present invention is the electromagnetic actuator according to any one of the first to fourth aspects, wherein the movable portion and the drive shaft are integrally molded by sintering ceramic powder. And

  According to this configuration, the production efficiency of the electromagnetic actuator can be improved as compared with a configuration in which the movable portion and the drive shaft are separately formed and then joined together. When the above configuration is applied to the invention described in claim 3, ceramic powder in which magnetic powder is uniformly dispersed is put into a sintering mold so that the movable part and the drive shaft are integrally molded. Alternatively, the movable portion and the drive shaft may be integrally formed in a state where the magnetic powder is unevenly distributed in the portion that becomes the movable portion in the sintering mold. However, since the magnetic substance powder has a higher specific gravity than the ceramic powder, it is desirable to adopt the latter molding method in order to reduce the weight. In addition, when the above configuration is applied to the invention described in claim 4, after the movable portion and the drive shaft are integrally formed, the magnetic material layer is formed by laminating the magnetic material on the movable portion.

  A sixth aspect of the invention is an injector of a common rail type diesel engine comprising the electromagnetic actuator according to any one of the first to fifth aspects, wherein the electromagnetic actuator is incorporated and a fuel passage is formed. A housing, a needle valve that is supported in the housing so as to be reciprocable and that opens and closes a nozzle hole based on a fuel pressure in the fuel passage, and an overflow passage that is formed in the housing and overflows fuel from the fuel passage A valve portion for opening and closing the overflow passage is formed on the drive shaft, and the drive shaft is driven through energization control of the electromagnet to close the overflow passage at the valve portion. Fuel overflow from the fuel passage to the overflow passage is stopped to stop fuel injection, while the overflow passage is opened and fuel flows from the fuel passage to the overflow passage. It was allowed to overflow and be required to run the fuel injection.

  In an injector of a common rail type diesel engine, high operation responsiveness is required because multistage injection for injecting a minute amount of fuel in a short period of time, such as pilot injection, post injection, or split injection, is executed. In this regard, according to the configuration of the sixth aspect, fuel injection can be executed with high operation responsiveness, and more precise fuel injection control can be performed.

(First embodiment)
Hereinafter, a first embodiment in which an injector of a common rail diesel engine according to the present invention is embodied will be described with reference to FIG. The injector 1 according to the present embodiment is connected to a common rail (not shown), and a high pressure fuel stored in the common rail is set in a combustion chamber (not shown) with a fuel injection timing and an injection mode set based on an engine operating state. Supply spray.

  As shown in FIG. 1, a housing 2 of the injector 1 has a supply passage 4 connected to a common rail and a return passage 5 for returning fuel to a fuel tank (not shown). . Further, a sac 27 to which high-pressure fuel is supplied from the supply passage 4 and a plurality of jets communicating the inside of the sac 27 and the outside of the housing 2 are provided at the front end side portion (the lower side portion of the figure) of the housing 2. A hole 3 is formed. These nozzle holes 3 are opened and closed by a needle valve 23 accommodated by the housing 2. The needle valve 23 includes a valve portion 24 for opening and closing the nozzle hole 3 and a flange 28 supported by the housing 2 so as to be reciprocally movable. The fuel pressure of the sac 27 acts on the front end surface of the flange 28, and the needle valve 23 is urged in the valve opening direction by a force based on the fuel pressure.

  A cylinder 8 is formed inside the housing 2, and a piston 21 is accommodated in the cylinder 8 so as to be capable of reciprocating. The piston 21 is connected to a needle valve 23 via a connecting shaft 22. The needle valve 23 including the piston 21 and the connecting shaft 22 is urged in the valve closing direction by a spring 25 provided inside the housing 2.

  Further, a back pressure control chamber 20 is defined in the cylinder 8 by an inner wall surface thereof and a base end side (upper side in FIG. 1) of the piston 21. The back pressure control chamber 20 is supplied with fuel from the common rail through the supply passage 4. The reciprocating motion of the piston 21 is controlled based on the fuel pressure in the back pressure control chamber 20, and the needle valve 23 is driven to open and close accordingly.

  In the housing 2, an orifice plate 16 is fitted on the proximal end side of the back pressure control chamber 20. An orifice hole 17 that communicates with the back pressure control chamber 20 is formed at a substantially central portion of the orifice plate 16.

  Next, an electromagnetic actuator 10 for controlling fuel injection built in the housing 2, specifically, an electromagnetic valve 10 that controls the fuel pressure in the back pressure control chamber 20 by opening and closing the orifice hole 17 of the orifice plate 16, This will be described with reference to FIG.

  The electromagnetic valve 10 includes an electromagnet 11, a disc-shaped movable portion 12 that is displaced based on the electromagnetic force of the electromagnet 11, and a drive shaft 13 that is displaced together with the movable portion 12. The drive shaft 13 is reciprocally supported by a bearing 18 that is positioned on the proximal end side of the orifice plate 16 and is fixed to the housing 2, and a valve portion 14 that opens and closes the orifice hole 17 is attached to the distal end portion thereof. It has been. The length of the portion of the drive shaft 13 positioned on the proximal end side of the movable portion 12 is set so that the movable portion 12 and the bearing 18 do not come into contact with each other when the orifice hole 17 is closed by the valve portion 14. ing.

  In the housing 2, a housing space 2 </ b> C and a groove 2 </ b> A to which the return passage 5 is connected are formed on the proximal end side of the bearing 18. Then, the electromagnet 11 is accommodated in the groove 2A, and the movable portion 12 is accommodated in the accommodating space 2C. The movable portion 12 is formed with a plurality of communication holes 19 for communicating a portion located on the distal end side with respect to the movable portion 12 and a portion located on the proximal end side in the accommodating space 2C.

  The drive shaft 13 extends from the central portion of the movable portion 12 to the distal end side and the proximal end side, and the distal end side portion is inserted into the bearing 18 and supported. A discharge groove 18 a extending along the axial direction of the drive shaft 13 is formed on the inner peripheral surface of the bearing 18. Therefore, the back pressure control chamber 20 can communicate with the return passage 5 through the orifice hole 17, the inside of the bearing 18, the discharge groove 18a, and the accommodation space 2C.

  Moreover, the movable part 12 and the drive shaft 13 described above are integrally molded by sintering ceramic powder containing magnetic powder. Specifically, the movable portion 12 and the drive shaft 13 are integrally molded in a state where a larger amount of magnetic powder is unevenly distributed in the portion that becomes the movable portion 12 in the sintering mold. Thereby, the movable part 12 is formed of a ceramic material and carries a magnetizable magnetic body. Here, as the ceramic powder, for example, powder of aluminum carbide, tungsten carbide, silicon nitride, silicon carbide or the like is used, and as the magnetic powder, powder of magnetic material such as iron, cobalt, nickel or the like is used. Then, after the movable portion 12 and the drive shaft 13 are integrally molded in this way, the valve portion 14 is attached to the distal end portion of the drive shaft 13. The amount of magnetic powder necessary for attracting the movable portion 12 by the electromagnetic force of the electromagnet 11, the uneven distribution mode, and the like are based on theoretical values and experiments calculated based on the design values of each component of the electromagnetic valve 10. It is determined by the set experimental value.

  Moreover, since the valve part 14 collides with the orifice plate 16 at the time of fuel injection, it is desirable to form the valve part 14 from a metal material or a ceramic material excellent in wear resistance and impact resistance. Further, here, the movable portion 12 and the drive shaft 13 are integrally molded, and then the valve portion 14 formed as a separate member is attached to the distal end portion of the drive shaft 13. However, the movable portion 12 and the drive shaft 13 are integrally molded with the drive shaft 13. Also good. In this case, the valve portion 14 may be formed of the same material as that of the drive shaft 13, but a sintered material different from the drive shaft 13, preferably higher, in the portion that becomes the valve portion 14 in the sintering mold. The valve portion 14 can be integrally formed with the drive shaft 13 by unevenly distributing a material having wear resistance and impact resistance.

  In the housing 2, the portion facing the tip portion 13 a of the drive shaft 13 is brought into contact with the tip portion 13 a of the drive shaft 13 when the movable portion 12 is attracted by the electromagnet 11, so that the movable portion 12 and the electromagnet 11 collide with each other. The stopper 7 for avoiding is formed. The stopper 7 is formed with a hole 2 </ b> B extending along the axial direction of the drive shaft 13 and a spring 15 that urges the drive shaft 13 toward the orifice hole 17.

  The fuel injection control of the injector 1 is executed by the electronic control unit 6 that performs various control of the engine. The electronic control unit 6 includes a CPU, a memory, a drive circuit for supplying current to the electromagnet 11, and an input circuit for receiving output signals from various sensors (all not shown). Then, the electronic control unit 6 sets the fuel injection timing and the injection mode based on the input signals of various sensors, and executes the fuel injection by controlling the energization of the electromagnet 11 based on them.

  Specifically, when the movable portion 12 is attracted by the electromagnetic force of the electromagnet 11, the drive shaft 13 is displaced to the electromagnet 11 side together with the movable portion 12. In accordance with this displacement, the valve portion 14 is separated from the orifice plate 16 and the orifice hole 17 is opened, so that the fuel in the back pressure control chamber 20 contains the orifice hole 17, the inside of the bearing 18, the discharge groove 18 a, and the housing. The fuel flows into the return passage 5 via the space 2C, and the fuel pressure in the back pressure control chamber 20 decreases. Therefore, the needle valve 23 is moved in the valve opening direction by the fuel pressure of the sac 27 to open the injection hole 3, and fuel is injected from the injection hole 3.

  On the other hand, when the energization of the electromagnet 11 is stopped, the drive shaft 13 is urged toward the orifice hole 17 by the urging force of the spring 15, the valve portion 14 contacts the orifice plate 16, and the orifice hole 17 is closed. As a result, the fuel pressure in the back pressure control chamber 20 is increased, so that the needle valve 23 is urged toward the nozzle hole 3 by the urging force based on the urging force of the spring 25 and the fuel pressure in the back pressure control chamber 20. The valve part 24 of 23 contacts the seat part 26, the injection hole 3 is closed, and fuel injection is stopped.

  The supply passage 4, the sac 27, and the back pressure control chamber 20 correspond to a fuel passage for supplying fuel pressure to the needle valve 23, and the orifice hole 17, the inside of the bearing 18, the discharge groove 18a, the accommodation space 2C, and the return passage. Reference numeral 5 corresponds to an overflow passage for overflowing fuel from the fuel passage. Further, the bearing 18 that supports the drive shaft 13 so as to reciprocate corresponds to a guide portion that guides the drive shaft 13 when the drive shaft 13 is displaced.

According to 1st Embodiment described above, there can exist the following effects.
(1) Since both the movable portion 12 and the drive shaft 13 are formed of a ceramic material, the weight of the movable portion 12 and the drive shaft 13 can be reduced, and the operation responsiveness of the solenoid valve 10 is improved. To be able to. Therefore, even in the injector 1 of the common rail type diesel engine in which multistage injection for injecting a small amount of fuel in a short period of time such as pilot injection, post injection, or split injection is performed as in the present embodiment. Fuel injection can be executed with operation responsiveness, and more precise fuel injection control can be performed.

  (2) Further, the drive shaft 13 is supported by the bearing 18 and reciprocates so that the support portion is likely to be worn and seized. However, the drive shaft 13 is made of a ceramic material. Therefore, the wear resistance and seizure resistance can be improved as compared with metal materials.

  (3) Since the movable portion 12 and the drive shaft 13 are integrally molded, the production efficiency of the electromagnetic valve 10 can be improved as compared with a configuration in which the movable portion 12 and the drive shaft 13 are separately formed and then joined together. become.

  (4) Since the magnetic powder is unevenly distributed in the movable portion 12, the ceramic powder in which the magnetic powder is uniformly dispersed is put into a sintering mold, and the movable portion 12 and the drive shaft 13 are integrally molded. The amount of magnetic powder can be reduced as compared with the above, and further weight reduction can be achieved.

  (5) Since the movable portion 12 is not formed of only a metal-based material but is formed of a mixed material of a metal-based material and a ceramic material, metal impurities contained in the fuel adhere to the movable portion 12 and deposit as deposits. This can be suppressed, and the deterioration of the operability of the solenoid valve 10 due to this can be suppressed.

(Second Embodiment)
A second embodiment in which the present invention is applied to an electromagnetic actuator for driving an intake valve of an engine will be described below with reference to FIG.

  As shown in FIG. 3, the cylinder head 42 provided with the intake valve 200 is formed with an intake port 43 to which intake air is supplied. In addition, a valve seat 44 on which the valve body 35 of the intake valve 200 is seated is attached to the periphery of the intake port 43. Then, the intake port 43 is opened and closed by the valve body 35, whereby the intake air is supplied to the combustion chamber 41.

  The electromagnetic actuator 30 built in the housing (not shown) of the intake valve 200 includes a valve closing electromagnet 32 including an upper core 50 and an upper coil 51, and a valve opening electromagnet 33 including a lower core 60 and a lower coil 61. In addition to these, the electromagnetic actuator 30 is disposed between the electromagnets 32 and 33 and is displaced based on the electromagnetic force of the electromagnets 32 and 33, and the drive shaft 34 that is displaced together with the movable part 31. And. And the said valve body 35 is attached to the front-end | tip part (lower part of the figure) of this drive shaft 34. As shown in FIG.

  The movable portion 31 and the drive shaft 34 are integrally formed by sintering ceramic powder such as aluminum carbide, tungsten carbide, silicon nitride, or silicon carbide. In addition, magnetic layers 31 a and 31 b made of a magnetic material are laminated on the surfaces of the movable portion 31 that face the electromagnets 32 and 33, respectively. These magnetic layers 31 a and 31 b are laminated on both surfaces of the movable portion 31 after the movable portion 31 and the drive shaft 34 are integrally molded. Thereby, the movable part 31 is formed of a ceramic material and carries a magnetizable magnetic body. The magnetic layers 31a and 31b are made of a magnetic material such as iron, cobalt, or nickel. Further, the thickness and shape of the magnetic layer necessary for attracting the movable portion 31 by the electromagnetic force of the electromagnets 32 and 33 are theoretical values calculated based on the design values of the components of the electromagnetic actuator 30, It is determined by the experimental value set based on the experiment.

  The drive shaft 34 extends substantially vertically from the central portion of the movable portion 31 to both sides thereof, and also has a hole 50a in the central portion of the upper core 50, a hole 60a in the central portion of the lower core 60, and a hole 42a formed in the cylinder head 42. It is inserted and supported so that it can reciprocate. Further, the drive shaft 34 and the valve body 35 are disposed between an upper retainer 53 fixed to the base end portion (the upper portion in the figure) of the drive shaft 34 and an upper cap 52 provided in the housing of the intake valve 200. An upper spring 54 that urges the valve in the valve opening direction is provided. On the other hand, a lower spring 64 that biases the drive shaft 34 and the valve body 35 in the valve closing direction is provided between the lower retainer 63 fixed to a substantially central portion in the axial direction of the drive shaft 34 and the cylinder head 42. Yes. The upper core 50, the lower core 60, and the cylinder head 42 that support the drive shaft 34 so as to reciprocate correspond to guide portions that guide the drive shaft 34 when the drive shaft 34 is displaced.

  The opening / closing control of the intake valve 200 is executed by an electronic control unit 40 that performs overall control of the engine. This electronic control device 40 is provided in a displacement sensor for detecting the displacement amount of the valve body 35 and an internal combustion engine, in addition to a CPU, a memory, and a drive circuit for supplying current to the coils 51 and 61 of the electromagnets 32 and 33. An input circuit (not shown) for receiving detection signals from various sensors is provided. Then, the opening / closing timing and opening / closing mode of the intake valve 200 are set based on the input signals of various sensors, and the electromagnets 32 and 33 are energized and controlled based on them to generate electromagnetic force, thereby controlling the opening / closing of the intake valve 200. .

  Specifically, when the movable portion 31 is attracted by the electromagnetic force of the valve opening electromagnet 33 and is displaced in the direction of the electromagnet 33, the drive shaft 34 and the valve body 35 are displaced in the valve opening direction along with this displacement. As a result, the valve body 35 is separated from the valve seat 44, the intake port 43 is opened, and intake air is supplied to the combustion chamber 41.

  On the other hand, when the movable part 31 is displaced in the direction of the electromagnet 32 by being attracted by the electromagnetic force of the valve closing electromagnet 32, the drive shaft 34 and the valve body 35 are displaced in the valve closing direction along with this displacement. As a result, the valve body 35 is seated on the valve seat 44, the intake port 43 is closed, and the supply of intake air to the combustion chamber 41 is stopped.

According to the second embodiment described above, the following effects (6) and (7) can be obtained.
(6) Since both the movable portion 31 and the drive shaft 34 are formed of a ceramic material, the movable portion 31 and the drive shaft 34 can be reduced in weight, and the operation responsiveness of the electromagnetic actuator 30 is improved. Will be able to. Therefore, even in the intake valve 200 that requires precise opening / closing control of the intake port 43 based on the engine operating state as in this embodiment, it can be opened / closed with high operation responsiveness. . Therefore, more precise opening / closing control can be performed, and as a result, engine output can be improved and early stabilization at engine start can be achieved.

  (7) Since the drive shaft 34 is supported by the upper core 50, the lower core 60 and the cylinder head 42 and reciprocates, the support portion is likely to be worn or seized, but the drive shaft 34 is formed of a ceramic material. Therefore, the wear resistance and seizure resistance can be enhanced as compared with the metal-based material.

(Third embodiment)
Hereinafter, a third embodiment in which the present invention is applied to an electromagnetic actuator for driving an injector of a gasoline engine will be described with reference to FIG.

  As shown in FIG. 4, a fuel passage 104 extending from the base end side (upper side in FIG. 4) to the distal end side (lower side in FIG. 4) is formed inside the housing 102 of the injector 100. . In addition, a plurality of injection holes 103 that communicate the inside and the outside of the housing 102 are formed in the front end side portion (the lower portion in the figure) of the housing 102.

  As in the first embodiment, the electromagnetic valve 110 built in the housing 102 includes an electromagnet 111, a movable portion 112 that is displaced based on the electromagnetic force of the electromagnet 111, and a drive shaft that is displaced together with the movable portion 112. 113. The movable portion 112 and the drive shaft 113 are integrally formed by sintering ceramic powder. In this case, similarly to the first embodiment, the movable portion 112 and the drive shaft 113 are integrally molded in a state where a larger amount of magnetic powder is unevenly distributed in the portion that becomes the movable portion 112 in the sintering mold. The movable portion 112 is formed with a plurality of communication holes 119 for communicating a portion located on the proximal end side with respect to the movable portion 112 and a portion located on the distal end side in the fuel passage 104. An outer peripheral portion of the movable portion 112 is in contact with a guide portion 116 formed on the housing 102, and the displacement is guided by the guide portion 116. The drive shaft 113 is integrally formed with a valve portion 114 that opens and closes the nozzle hole 103.

  Between the base end portion of the drive shaft 113 and the cylindrical member 107 fixed inside the housing 102, a spring 115 that urges the drive shaft 113, that is, the valve portion 114 in the valve closing direction, is provided.

  The fuel injection control of the injector 100 is executed by an electronic control unit 106 that performs overall control of the engine. The electronic control unit 106 sets the fuel injection timing and the injection mode based on the input signals of various sensors provided in the engine, and executes the fuel injection by controlling the energization of the electromagnet 111 based on them.

  Specifically, when the movable portion 112 is attracted by the electromagnetic force of the electromagnet 111, the drive shaft 113 is displaced to the electromagnet 111 side together with the movable portion 112. Then, the injection hole 103 is opened in accordance with this displacement, so that fuel is injected from the injection hole 103.

  On the other hand, when the energization of the electromagnet 111 is stopped, the drive shaft 113 is moved in the direction of closing the injection hole 103 by the urging force of the spring 115, and the injection hole 103 is closed by the valve portion 114 to stop the fuel injection. Is done.

According to 3rd Embodiment described above, in addition to the effect similar to said (3)-(5), there can exist the effect shown to the following (8) and (9).
(8) Since both the movable portion 112 and the drive shaft 113 are made of a ceramic material, the movable portion 112 and the drive shaft 113 can be reduced in weight, and the operation responsiveness of the solenoid valve 110 is improved. To be able to. Therefore, in the injector 100 to which the electromagnetic valve 110 is applied, fuel injection can be executed with high operation responsiveness.

(9) Further, since the outer peripheral portion of the movable portion 112 is supported by the guide portion 116 and reciprocates, wear and seizure are likely to occur in the outer peripheral portion, but the movable portion 112 is formed of a ceramic material. Therefore, the wear resistance and seizure resistance can be improved as compared with the case where the metal material alone is used.
(Other embodiments)
In addition, this invention is not limited to the structure illustrated in each said embodiment, It can also implement as the following forms which changed the same embodiment suitably, for example.

  In the second embodiment, the electromagnetic actuator is applied to the intake valve. However, the electromagnetic actuator may be applied to the exhaust valve. Even in this case, the exhaust valve can be opened and closed with high operation responsiveness.

-Although the example which attaches the valve part 14 formed as a separate member to the drive shaft 13 was shown in the said 1st Embodiment, the structure which forms a valve part integrally with a drive shaft is also employable.
In the first embodiment, the example in which the movable portion 12 and the drive shaft 13 are integrally formed in a state where the magnetic powder is unevenly distributed in the portion of the movable portion 12 has been described. Moreover, in the said 2nd Embodiment, after integrally forming the movable part 31 and the drive shaft 34, the example which laminate | stacks the magnetic body layers 31a and 31b on the surface which opposes the electromagnets 32 and 33 in the movable part 31 was shown, respectively. However, the present invention is not limited to these examples as long as the movable portion and the drive shaft are formed of a ceramic material and a magnetizable magnetic material is supported on the movable portion. For example, in the first embodiment, as exemplified in the second embodiment, a magnetic material layer may be stacked on the movable portion to carry the magnetic material. Even in this case, the effects shown in the above (1), (2), and (5) can be achieved. Further, in the second embodiment, as exemplified in the first embodiment, the magnetic material may be carried by mixing the magnetic powder in the movable portion. Even in this case, it is possible to achieve the effects similar to the above (3), (4), (6), (7).

  In the first embodiment, the example in which the movable portion 12 and the drive shaft 13 are integrally formed in a state where the magnetic powder is unevenly distributed in the portion of the movable portion 12 is shown. You may make it integrate them by shape | molding with another type | mold and joining both. Specifically, a disk-shaped movable part with a hole formed in the center is molded with ceramic powder mixed with magnetic powder, while the drive shaft part is molded with ceramic powder and driven into the hole in the movable part. What is necessary is just to join both by inserting a shaft.

  In the first embodiment, the example in which the movable portion 12 and the drive shaft 13 are integrally formed in a state where the magnetic powder is unevenly distributed in the portion of the movable portion 12 has been described. However, the movable part and the drive shaft may be integrally molded by putting ceramic powder in which the magnetic powder is uniformly dispersed in the entire movable part and the drive shaft into a sintering mold. In this case, it is possible to improve the production efficiency of the electromagnetic actuator as compared with a configuration in which the movable part and the drive shaft are integrally formed in a state where the magnetic powder is unevenly distributed in the movable part. From the viewpoint of the operation response of the electromagnetic actuator, it is preferable that the movable part and the drive shaft are light, and that the magnetic powder has a higher specific gravity than the ceramic powder, so that the magnetic powder is preferably as small as possible. It is desirable to determine the amount of magnetic powder to be mixed in consideration of the fact that the movable part needs to have enough magnetism to be attracted by force.

  In each of the above embodiments, the present invention is embodied as an electromagnetic actuator provided in various valves of the engine, but the application target of the present invention is not limited thereto. In short, the present invention can be applied to any electromagnetic actuator provided with a movable portion and a drive shaft that are driven by the electromagnetic force of the electromagnet. In this case, the movable portion and the drive shaft are also applicable. It becomes possible to improve the operation responsiveness.

1 is a longitudinal sectional view of an injector of a common rail diesel engine according to a first embodiment of the present invention. The fragmentary sectional view shown about the solenoid valve concerning the embodiment and sectional structure of the periphery. The longitudinal cross-sectional view of the intake valve which incorporates the electromagnetic actuator concerning 2nd Embodiment. The longitudinal cross-sectional view of the injector which incorporates the electromagnetic actuator concerning 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,100 ... Injector, 2,102 ... Housing, 2C ... Accommodating space, 3,103 ... Injection hole, 4 ... Supply passage, 5 ... Return passage, 6, 40, 106 ... Electronic control unit, 7 ... Stopper, 8 ... Cylinder, 10, 110 ... Solenoid valve, 11, 111 ... Electromagnet, 12, 31, 112 ... Movable part, 13, 34, 113 ... Drive shaft, 14, 24, 114 ... Valve part, 15, 25, 115 ... Spring, DESCRIPTION OF SYMBOLS 16 ... Orifice plate, 17 ... Orifice hole, 18 ... Bearing, 18a ... Discharge groove, 19,119 ... Communication hole, 20 ... Back pressure control chamber, 21 ... Piston, 22 ... Connecting shaft, 23 ... Needle valve, 26 ... Seat 27: Sack, 28 ... Flange, 30 ... Electromagnetic actuator, 31a, 31b ... Magnetic material layer, 32 ... Electromagnet for valve closing, 33 ... Electromagnet for valve opening, 35 ... Valve body, 41 ... Combustion chamber, 42 ... Linda head, 43 ... intake port, 44 ... valve seat, 50 ... upper core, 51 ... upper coil, 52 ... upper cap, 53 ... upper retainer, 54 ... upper spring, 60 ... lower core, 61 ... lower coil, 63 ... lower retainer, 64 ... Lower spring, 104 ... fuel passage, 107 ... cylindrical member, 116 ... guide part, 200 ... intake valve.

Claims (6)

In an electromagnetic actuator comprising a movable part that is displaced based on the electromagnetic force of an electromagnet, and a drive shaft that is displaced together with the movable part,
The movable part and the drive shaft are made of a ceramic material, and a magnetizable magnetic material is supported on the movable part. The electromagnetic actuator according to claim 1,
An electromagnetic actuator characterized in that at least one of the drive shaft and the movable portion is guided by a guide portion when displaced. The electromagnetic actuator according to claim 1 or 2,
The movable actuator is formed of ceramic powder mixed with magnetic powder and sintered and molded. The electromagnetic actuator according to claim 1 or 2,
An electromagnetic actuator, wherein the movable part is formed by laminating a magnetic material layer made of a magnetic material on a surface facing the electromagnet. In the electromagnetic actuator according to any one of claims 1 to 4,
The electromagnetic actuator, wherein the movable part and the drive shaft are integrally formed by sintering ceramic powder. A common rail diesel engine injector comprising the electromagnetic actuator according to any one of claims 1 to 5,
A housing that includes the electromagnetic actuator and has a fuel passage formed therein, a needle valve that is supported in the housing so as to be reciprocable and that opens and closes a nozzle hole based on the fuel pressure in the fuel passage, and is formed in the housing. An overflow passage for overflowing fuel from the fuel passage,
The drive shaft is formed with a valve portion that opens and closes the overflow passage. By driving the drive shaft through energization control of the electromagnet, the overflow passage is closed by the valve portion, and the fuel passage is disengaged from the fuel passage. The fuel injection to the overflow passage is stopped by stopping the fuel injection, while the overflow passage is opened and the fuel is overflowed from the fuel passage to the overflow passage to execute the fuel injection. Common rail type diesel engine injector.

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